# Removing a piezo transducer from a reference design

I'm building a system which is intended to supply a microcontroller with a smoke-detection alarm. I'm currently intending to base the circuit on a Microchip RE46C190, which I can source fairly easily.

The datasheet has a typical-application circuit on page 21 which looks suitable for adaptation, but I need advice on how to remove the piezo transducer from the design (as I don't require an audible output; I intend to link the IO pin to the microcontroller). I gather that FEED will need to be tied to one of the rails (when not in test mode, anyway), but what should I do with pins HS and HB which are intended to drive the transducer? Can I simply leave then unconnected, and omit R3, R4 and C5?

• Well, I want to remove the components as there's no point including them if they're not going to do anything - but if I understand that logic correctly, by grounding FEED, HS will always be low, and HB will mirror the enable signal - which is straightforward enough to deal with. Thanks. – Andy S Feb 6 '13 at 15:08